Many pets suffer from dental health problems. A primary factor in the development of these problems is the formation of plaque on the surface of the teeth. Plaque contains bacteria and other components that adhere to the surface of the teeth, accumulating both above and below the gum line and leading to inflammation, or gingivitis, and malodors in the dental cavity.
Contributing to the problem is the formation of tartar or dental calculus (mineralized plaque). Dental calculus forms on the tooth surface at or above the gum line and serves as a substrate for additional accumulation of plaque. Apart from causing gum irritation and eventually periodontal disease if left untreated, the calculus has an unsightly appearance.
Animals in the wild are less susceptible than pets to the formation of plaque and calculus due to the nature of the foods that they eat; many of these foods mechanically abrade plaque and calculus from the teeth. Pets, however, are usually fed commercially available pet foods. While the commercially available pet foods are usually much better for the pet from a nutritional point of view, they in general do not subject the teeth of the pets to abrasive forces sufficient to clean the teeth. Even dried kibbles are able to abrade the teeth only to a very limited extent. This is because dried kibbles usually crumble when chewed by the pet.
There have been various attempts to deal with the problem. One of these attempts centers around the use of chews made from rawhide or rawhide substitutes. By gnawing or chewing on the chews, the pet abrades calculus and plaque from its teeth. Further, as described in European patent application 0272968, various oral care agents may be incorporated into the chews. A drawback with this approach is that it is only really applicable to dogs. Cats are usually not in the habit of gnawing or chewing on a chew. Also, rawhide based products are expensive.
Another approach has been to incorporate oral care agents into certain pet foods. For example, U.S. Pat. No. 5,000,940 discloses baked dog biscuits which contain a tetrasodium pyrophosphate salt. The salt is reported in the patent to cause a reduction in calculus accumulation. Also, European patent application 0205354 discloses baked dog biscuits which contain vegetable fibers to abrade the teeth of the dog when chewed. The drawback with both these products is that the biscuit crumbles upon being bitten. Hence the dog does not chew the product and little abrasion occurs. This reduces the efficacy of the products. Also, the products are not really suitable for cats.
A further approach is described in U.S. Pat. No. 5,431,927. The pet food described in this patent is a dried product which contains aligned fibers and which, when chewed, fractures along striations rather then crumbles. This is reported in the patent to retain the product in contact with the animal's teeth for a longer period of time hence enhancing the abrasive effect. However, the product must be produced using a specially coated die which permits laminar flow conditions within the die. The laminar flow conditions are reported to cause alignment of the fibers within the product leading to the fracturing of the product when bitten. The use of these dies unnecessarily complicates production of the product.
Therefore there is a need for a dental care pet food which is applicable to both dogs and cats and which may be produced without the need for special processing.